Control Method For Actuating a Thrust Reverser

ABSTRACT

The invention relates to a control method for opening or closing a turbojet engine thrust reverser ( 1 ) by using at least one mobile cowl ( 2 ) displaceable by means of at least one electric motor ( 7 ) consisting in analysing at least one parameter representative for a pressure in the turbojet engine jet and in carrying out an operating sequence in which the operating parameters of the electric motor ( 7 ) are adjusted to a situation.

FIELD OF THE INVENTION

The present invention relates to a method for controlling a turbojetthrust reverser, employing at least one moving cover that can be movedby means of at least one electric motor. The invention also relates to athrust reverser suited to such a control method.

BACKGROUND OF THE INVENTION

The purpose of a thrust reverser when an airplane lands is to improvethe ability of an airplane to brake by redirecting forward at least someof the thrust generated by the turbojet. In this phase, the reverserobstructs the jet pipe and directs the jet ejected from the enginetoward the front of the nacelle, thereby generating a reverse thrustwhich adds to the braking of the wheels of the airplane.

The means employed to redirect the jet in this way vary according to thetype of reverser. However, in all cases, the structure of a reversercomprises moving covers which can be moved between, on the one hand, adeployed position in which they open up within the nacelle a passageintended for the diverted jet and, on the other hand, a retractedposition in which they close off this passage. These moving covers canalso perform a deflecting function or may simply activate otherdeflecting means.

In cascade-type thrust reversers, for example, the moving covers slidealong rails so that on retreating during the opening phase, they uncoverthe cascades of deflector vanes positioned within the thickness of thenacelle. A system of link rods connects this moving cover to lockingdoors which deploy into the jet pipe duct and block off the direct jetoutlet. In door-type thrust reversers by contrast, each moving coverpivots in such a way as to block off the jet and deflect it and istherefore active in this redirection.

In general, the moving covers are actuated by hydraulic or pneumaticactuators which require a pressurized-fluid transport network. Thispressurized fluid is conventionally obtained either by bleeding air offthe turbojet in the case of a pneumatic system or by tapping off theairplane hydraulic circuit. Such systems require a great deal ofmaintenance because the slightest leak in the hydraulic or pneumaticnetwork may be difficult to detect and carries the risk of havingserious consequences both for the reverser and for other parts of thenacelle. Furthermore, because of the lack of space available in thefront section of the reverser, fitting and protecting such a circuit areparticularly tricky and space-consuming operations.

Another disadvantage with the hydraulic and pneumatic systems is thatthe actuators or the motor always deliver the maximum power for whichthey were designed and which has to correspond to the power needed toopen or close the reverser under heavily loaded landing or takeoffsituations. More specifically, these are, in particular, opening (ordeployment) in the event of an aborted takeoff, and closure (orretraction) in the event of an aborted landing, which scenarios requirea great deal more motive power than is required under normalcircumstances to overcome the stresses associated with a very highturbojet speed. The issue in particular is one of being able to provideenough power that, on the one hand, during opening, the strongdepression created by the direct jet which opposes the onset of openingof the moving cover and detachment of its closure seal can be overcomeand, on the other hand, upon closing, the higher opposing aerodynamicforces can be overcome. Although rare, these operating scenarios have ofcourse to be taken into consideration for safety reasons.

Because the power delivered by the actuators is always the maximum powerneeded to ensure that the reverser works in these heavily ladenscenarios, the loads exerted on the structures and the equipments arealways the highest loads, therefore leading to premature fatigue wear ofthe various components of the reverser. Furthermore, should a componentof the reverser become jammed, the dynamic and static loads will also bevery high.

For example, if the latches that latch the reverser closed becomejammed, the dynamic loadings due to a shock of the moving cover inmotion will be very great. The latch has to be designed to be able towithstand this shock with a motor (or a system) acting at full speed andfull power. It will therefore be necessary for this latch to beoverengineered to the detriment of the overall mass. This same line ofarguing may apply to other components of the reverser.

More specifically, with a pneumatic or hydraulic system, the probabilityof a shock occurring at full power is equal to the probability of thereverser becoming jammed because full power is delivered each time it isused. According to manufacturer standards, reverser jamming is thereforean extreme case the probability of occurrence of which is too high to beable to tolerate plastic deformation of the components. The solutionadopted to avoid such deformations is for the components of the thrustreverser to be overengineered at the expense of the overall mass.

It should be noted here that the mass of the equipments is an essentialaspect in aeronautical design and that the thrust reverser constitutesthe heaviest nacelle subassembly. It is therefore advantageous to seekto reduce this mass as far as possible while at the same time meetingsafety and strength standards.

In order to offset the disadvantages associated with the pneumatic andhydraulic systems, thrust reverser manufacturers have sought to replacethem and to equip their reversers as far as possible withelectromechanical actuators which are lighter in weight and morereliable. A reverser such as this is described in document EP 0 843 089.However, the issue of the forces exerted on the structure has not beenentirely resolved because it is still necessary for the electric motorsto be capable of operating the reverser under the heavily ladenscenarios.

SUMMARY

It is an object of the present invention to overcome the aforementioneddisadvantages and, in particular, to optimize the mass saving permittedby the use of electromechanical actuators and to improve the longevityof the thrust reverser and for that reason the invention consists in acontrol method for opening or closing a turbojet thrust reverseremploying at least one moving cover that can be moved by means of atleast one electric motor, characterized in that it comprises, for theopening and/or closing phase, the following steps aimed at:

-   -   analyzing at least one parameter representative of the pressure        in the turbojet stream,    -   executing an operating sequence in which the operating        parameters of the electric motor are suited to the situation.

Thus, when the thrust reverser has to be actuated in a scenario in whichsubstantial forces need to be provided, that is to say in the event ofan aborted takeoff or of an aborted landing for example, analysis of aparameter representative of the pressure in the turbojet stream,indicative of the operating speed and of the forces to be supplied inorder to open or close the reverser, makes it possible to detect thatone of these situations has arisen and adapt the parameters of saidreverser opening or closing sequence accordingly. As a subsidiaryeffect, analyzing the representative parameter therefore makes itpossible not to execute the operating sequence needlessly with electricmotor operating parameters that are not needed in the event of normalactuation. In so doing, the operating parameters intended for scenariosinvolving heavy loadings are no longer applied as a matter of routinebut are reserved merely for heavily laden scenarios. The probability ofa shock occurring at high engine power is, by virtue of the methodaccording to the invention, considerably reduced because this event canarise only when this high power is required given the representativeparameter. The occurrence of a shock at full power is therefore nolonger an extreme case because the probability of the reverser becomingjammed is, by virtue of the method according to the invention,multiplied by the probability of the reverser operating in a highlyladen situation, and is therefore greatly reduced. According tomanufacturer standards, this is an extreme case which allows a certainplastic deformation of the components, making it possible to scale downcertain components.

As a preference, the representative parameter analyzed is obtained fromthe speed of the turbojet low pressure compressor shaft. Therepresentative parameter may, depending on the type of turbojet,directly be the rotational speed of the shaft itself, or a reduced speedthereof if a reduction gearbox is positioned between the compressorshaft and a fan. Specifically, only the rotational speed actuallytransmitted to the fan is a parameter representative of the pressure inthe turbojet stream. This value can readily be obtained via theelectronic system that controls the turbojet and known by itsEnglish-language acronym FADEC which stands for Full Authority DigitalEngine Control. Of course, other values may be used such as, forexample, the air pressure in the turbojet. It is also possible toanalyze several representative parameters such as, for example, thereduced rotational speed of the low-pressure shaft corrected by theambient temperature and ambient pressure values, so as to obtain a morerefined and more reliable analysis.

Advantageously, the sequence executed is chosen from at least twopredetermined sequences that correspond to instances in which theturbojet is at low speed and at high speed, respectively. A low turbojetspeed means the turbojet operating speeds during normal deployment orretraction of the reverser, and instances in which the reverser ismaneuvered during maintenance operations, with the turbojet then notoperating. This speed generally corresponds to low pressure compressorshaft rotational speeds of below about 30 to 40% of the maximum speedset by the manufacturer of the turbojet. This value is not an absolutereference and may be altered according to the characteristics of theturbojet and according to the actual loadings exerted on the movingcovers as they move. Conversely, low pressure compressor shaftrotational speeds in excess of about 30 to 40% of the maximum speedcorrespond to a high speed. It should also be noted that this dividingvalue separating high and low speeds is not necessarily the same foropening phases as it is for closing phases.

Indeed, as explained earlier, upon opening, the issue will essentiallybe one of supplying the power needed to detach the moving cover, whereasupon closure, the issue will be rather one of overcoming the externalair stream that opposes closure of the moving cover. The progressions ofthese two constraints as the turbojet speed changes are not the same andit will therefore be advantageous to provide different low speed/highspeed dividing values for opening by comparison with closure.

Advantageously, when the operating sequence is being executed, theelectric motor delivers a torque less than or equal to a maximum limitvalue. Thus, the torque delivered by the electric motor to actuate themoving covers is calibrated and can be limited to the torque that isjust enough to move the moving covers under the turbojet speedconditions. Unlike the pneumatic or hydraulic systems already described,the power of an electric motor depends on the current supplied to thismotor and can be regulated so that the motor delivers its maximum poweronly if needed. By limiting the application of a high torque toinstances where the loading is high, the probability that the reverserwill have to withstand high static loadings in the event of jamming willbe greatly reduced because it is multiplied by the probability of itbeing in a scenario in which there are high loads. Wear and fatigue ofreverser components are therefore reduced and, accordingly, the strengthand longevity of the reverser are thereby improved.

As a preference, when the value of the parameter representative of theturbojet speed lies within a predetermined range, the maximum limitvalue on the torque delivered by the electric motor is determined byapplying a function similar to the value of the representativeparameter. In this way, it is possible to provide at least one operatingsequence which will be executed for intermediate turbojet operatingspeeds. This makes it possible to fine-tune the parameters of theopening sequence.

More advantageously still, the operating sequence executed for aturbojet operating at low speed comprises a test step for testing theoperating status (rotating) of the electric motor which, in the eventthat the latter is not operating (not rotating), will cause theoperating sequence intended for a turbojet operating at a higher speedto be applied. A step such as this is particularly useful if analysis ofthe parameter representative of the turbojet speed is impossible or iserroneous and the sequence executed is the one intended for a turbojetoperating at low speed. In this case, if this sequence provesunsuitable, the sequence intended for heavily laden scenarios will beexecuted.

Advantageously also, the speed of the motor is limited at least at thestart of the operating sequence executed. By limiting the speed, thedynamic loadings and the inertial effects liable to be exerted on thereverser structure in the event of its being jammed are limited. Oncethe sensitive components such as the latches have been negotiated, it ispossible to set a higher second speed datum value.

As a preference, the operating sequence applied comprises at least onestep of checking and regulating the speed.

As a preference also, the operating sequence comprises a control loopfor checking the operating status of the electric motor and capable ofshutting this electric motor down. Thus, if any jamming is detected, theelectric motor can be stopped or kept on standby.

Advantageously, provision is made for an operating sequence to beinitiated by default if the representative parameter cannot be analyzed.This default sequence may be a sequence identical to one of the proposedoperating sequences or may be a special sequence.

The present invention also consists of a thrust reverser comprising atleast one moving cover that can be moved under the action of at leastone electric motor, characterized in that the electric motor iscontrolled via at least one control interface capable, in succession, ofanalyzing at least one parameter representative of the turbojet speedand of delivering at least one suitable operating datum value.

As a preference, the control interface is connected to a turbojetcontrol unit delivering the representative parameter.

Advantageously, the electric motor is a self-controlled synchronousmotor. An electric motor such as this is particularly well suited totorque and/or speed control. In addition, the rotational speed and thetorque delivered can readily be measured.

Advantageously also, the electric motor is torque controlled at constantspeed. As a preference, the interface comprises regulating means forregulating the torque delivered by the electric motor.

Advantageously, the control interface is capable of receiving a speeddatum value and of converting it into a torque instruction that itdelivers to the electric motor. As a preference, the control interfacecomprises regulating means for regulating the speed of the electricmotor.

BRIEF DESCRIPTION OF THE FIGURES

Implementation of the invention will be better understood through thedetailed description which is explained hereinafter with reference tothe attached drawing in which:

FIG. 1 is a partial perspective schematic view of a nacelleincorporating a cascade-type thrust reverser.

FIG. 2 is a schematic depiction of the moving covers and of theiractuating system.

FIG. 3 is a diagram representing the steps of operation of a controlmethod according to the invention for opening a thrust reverser.

FIG. 4 is a diagram representing the steps of operation of a controlmethod according to the invention for closing a thrust reverser.

FIG. 5 is a curve representing the maximum limit torque allowed in thereverser opening phase as a function of turbojet speed.

FIG. 6 is a curve representing the maximum limit torque allowed in thereverser closing phase as a function of turbojet speed.

FIG. 7 is a simplified depiction of the design of a control interfacewith which a reverser according to the invention is equipped.

DETAILED DESCRIPTION

Before describing an embodiment of the invention in detail, it isimportant to emphasize that the invention is not restricted to anyparticular type of reverser. Although it has been illustrated using acascade-type reverser, it can be implemented with thrust reversers ofdifferent designs, particularly of the clamshell door type.

FIG. 1 shows a schematic part view of a nacelle incorporating a thrustreverser 1. The turbojet is not depicted. This thrust reverser 1 has astructure comprising two semicircular moving covers 2 capable of slidingin order to uncover cascades 3 of deflector vanes positioned between themoving covers 2 and a cross section for the passage of the air flow 4that is to be deflected. Blocking doors 5 are positioned inside thestructure so that they can pivot and move from a position in which theydo not impede the passage of the flow of air 4 into a position in whichthey block off this passage. In order to coordinate the opening of themoving covers 2 with a shutting-off position of the blocking doors 5,the latter are mechanically connected to the moving cover 2 by hingesand to the fixed structure by a system of link rods (not depicted).

The movement of the moving covers 2 along the outside of the structureis performed by a collection of actuators 6 a, 6 b which are mounted ona front section inside which an electric motor 7 and flexibletransmission shafts 8 a, 8 b connected to the actuators 6 a, 6 b,respectively, in order to actuate them, are housed.

The system for actuating the moving covers 2 is depicted by itself inFIG. 2. Each moving cover 2 can be translated under the action of threeactuators 6 a, 6 b comprising a central actuator 6 a and two additionalactuators 6 b, actuated by a single electric motor 7 connected to acontrol interface 9. The power delivered by the electric motor 7 isfirst of all distributed to the central actuators 6 a via two flexibletransmission shafts 8 a and then to the additional actuators 6 b byflexible transmission shafts 8 b.

A diagram showing the steps of a method according to the invention foropening the thrust reverser 1 is given in FIG. 3.

First of all, the command 100 is given by the pilot to deploy the thrustreverser. This command is followed by a checking step 101 which will orwill not authorize deployment according to the status of the controlinterface 9. If the response from a control interface 9 is negative,then this control interface aborts 102 deployment and a message 103 issent via the control interface 9 to the instrument panel. It should benoted that certain aircraft manufacturers, for safety reasons, requirethat deployment or retraction be attempted even if the system does notauthorize opening. In this case, the checking step 101 is omitted andreplaced by one or more steps suited to this requirement.

A positive response from the control interface 9 initiates the onset ofdeployment 110.

First of all, the control interface 9 analyzes a parameterrepresentative of the operating speed of the turbojet obtained from aFADEC (not depicted) with which the turbojet is equipped. This analysisstep comprises a first substep 111, a second substep 112 and a thirdsubstep 113.

The first substep 111 consists in testing the availability of therepresentative parameter. If the value thereof cannot be obtained, thena default operating sequence is engaged. This default sequence may bethe same as or different from an existing operating sequence used fordefined values of the representative parameter. In this particularinstance, this default sequence is identical to a sequence intended forheavily laden scenarios that will be described later on.

The second substep 112 and the third substep 113 use the value of therepresentative parameter. This value in the example will be expressed asa percentage of the maximum turbojet speed as given by the manufacturer.In this example, there are three operating sequences comprising a normaloperating sequence 130 intended to be applied if the value of therepresentative parameter is less than N1% of the value corresponding toa maximum speed of the turbojet, an operating sequence for heavily ladenscenarios 140 (aborted takeoff or ATO in this example) intended to beapplied if the value of the representative parameter is greater than orequal to N2, and an intermediate sequence 150 intended to be applied forvalues of the representative parameter that range between N1 and N2.

Each operating sequence 130, 140, 150 will now be described.

The normal operating sequence 130 comprises conventional steps aimed atunlatching the reverser, then at switching on the electric motor 7. Thissequence comprises a regulating control loop aimed at keeping the torquedelivered by the electric motor 7 at a value below Trq1. In addition, acontrol loop 131 monitors the rotational speed of the electric motor 7and keeps it below 1750 revolutions per minute.

A test step 132 analyzes the travel covered by the moving covers 2. Ifthis is greater than 35 mm after about 300 ms, opening continues, themotor torque remaining limited to Trq1, and a command 161 fixes thespeed limit at 10740 revolutions per minute, which in this example isthe maximum speed of the motor. If it is not, that is to say if themoving covers 2 have not covered more than 35 mm of translationalmovement in less about 300 ms, that means that either the motor power isnot enough to open the reverser in the total time given or that themotor is jammed. A command 162 then sets the maximum motor torque to ahigher value Trq2. A test step 163 is then performed, the purpose ofthis being to determine whether the electric motor 7 is operating. If itis not operating, then a command 164 switches it to standby and a motorjammed message is sent in a step 165. If the electric motor 7 isoperating, the step 161 increasing the speed of opening is applied andopening continues until it reaches its conclusion.

The operating sequence for heavily laden conditions 140 differs from thenormal operating sequence 130 only in that the motor torque is limitedto Trq2. It should be noted that this operating sequence 140 is also thedefault sequence applied when the value of the representative parameteris not available.

The intermediate operating sequence 150 differs from the operatingsequence 130 only in that the motor torque is limited to a value Trqxdetermined by the application of a function similar to the value of therepresentative parameter. This similar function is defined such that, onthe one hand, the value of Trqx for a representative parameter equal toN1 is Trq1, and, on the other hand, the value of Trqx for arepresentative parameter equal to N2 is Trq2.

As a safety measure, it is possible to ensure that the operatingsequence for heavily loaded scenarios 140 comprises a checking stepwhich sends a message to the instrument panel when, for example, morethan three of the operating sequences for heavily laden scenarios 140have been performed by default.

Operating steps of a control method according to the invention forclosing the thrust reverser 1 are depicted in FIG. 4.

First of all, the command 200 is given by the pilot to retract thereverser. This command is followed by a checking step 201 which willeither authorize or not authorize retraction according to the status ofthe control interface 9. If the response from the control interface 9 isnegative then it aborts 202 retraction and a message 203 is sent via thecontrol interface 9 to the instrument panel.

A positive response from the control interface 9 initiates the onset ofretraction 210.

First of all, the control interface 9 analyzes the parameterrepresentative of the turbojet operating speed as obtained from theFADEC. This analysis step involves a first substep 211 and a secondsubstep 212.

The first substep 211 consists in testing the availability of therepresentative parameter. If the value thereof cannot be obtained, thena default operating sequence is initiated. In this particular instance,this default sequence is identical to a sequence intended for heavilyladen scenarios and which will be described later on.

The second substep 112 uses the value of the representative parameter todetermine, from between a normal operating sequence 230 and a operatingsequence for heavily laden scenarios 240, which sequence to apply.

The normal operating sequence 230 is applied if the value of therepresentative parameter is below a value N3 and involves theconventional steps aimed at switching on the electric motor 7 with aview to closing the reverser 1. This sequence comprises a control loopaimed at keeping the torque delivered by the electric motor 7 at a valuebelow Trq3.

The operating sequence for heavily laden scenarios 240 is applied if thevalue of the representative parameter is greater than N3 and differsfrom the normal operating sequence 230 only in that the motor torque islimited to a value Trq4 higher than Trq3.

Furthermore, a test step 231 aimed at checking the operation of theelectric motor 7 is provided at the start of the normal operatingsequence 230. If the motor is not turning then the sequence intended forheavily laden scenarios 240 is applied. If the electric motor 7 isoperating, its seed is increased by a command 250 but is nonethelesslimited to the maximum speed of the electric motor 7, which in thisexample is 9000 revolutions per minute. The motor torque is still keptbelow or equal to Trq3. Retraction continues until it is complete.

The sequence intended for heavily laden scenarios 240 also comprises atest step 241 aimed at analyzing the operation of the electric motor 7.If the electric motor 7 is not operating, then a command 242 switches itto standby. This is because switching to standby is preferable tocutting off the power supply because the aerodynamic forces naturallytend to try to open the moving covers 2 so it is necessary to maintain aminimum standby torque. A command 243 then sends a message to theinterface 9. If the electric motor 7 is operating, step 250 is appliedand retraction continues until it is complete.

FIGS. 5 and 6 show, for reverser 1 deployment and retractionrespectively, examples of profiles of the maximum limiting torque valuesallowed as a function of the value of the representative parameter ascome out of the methods described earlier and depicted in FIGS. 3 and 4.These profiles are intended to be programmed into the control interface9 and are used to determine the appropriate operating sequence.

FIG. 7 depicts, in a simplified way, the operating diagram of the maincircuits of a control interface 9 with which a thrust reverser 1according to the invention is equipped. The control interface 9 operatesthe electric motor 7 which consists of a self-controlled synchronousmotor capable of receiving torque or speed control commands.

An electric motor 7 such as this is particularly well suited to a methodaccording to the invention. Its operation relies on the interactionbetween a magnetic rotor field and a rotary magnetic stator field. In anelectric motor 7 such as this, a sensor detects the precise position ofthe rotor and allows a frequency converter to keep the angle between therotor and the rotary stator field equal to 90° so that the motor torqueis always at its maximum. Amplitude modulation of the rotary statorfield fixes the value of the motor torque. The sensor also providesinformation regarding the rotational speed of the electric motor 7.

In operation, in order for the speed to remain constant if the loaddecreases or increases, the motor torque has to be decreased orincreased. The amplitude of the rotary stator field will therefore bereduced or increased but the frequency of the field will be unchanged.

The interface receives a speed datum value 302 from which a comparator303 subtracts the current speed 304 of the electric motor 7. Thedifference between these speeds is fed into a speed regulator 305 whichcalculates the appropriate response in the form of a torque datum value306. This torque datum value 306 is fed through a comparator 307 whichsubtracts the current torque at 308 of the electric motor 7 from it.This difference is supplied to a torque regulator 309 which delivers theappropriate datum value 310 to the electric motor 7.

Although the invention has been described in conjunction with particularexemplary embodiments, it is obvious that it is not in any wayrestricted thereto and that it comprises all technical equivalents ofthe means described and combinations thereof where these fall within thescope of the invention.

1. A control method for opening or closing a turbojet thrust reverser,employing at least one moving cover that can be moved by means of atleast one electric motor, at the method comprising: analyzing at leastone parameter representative of the pressure in the turbojet stream,executing an operating sequence in which the operating parameters of theelectric motor are suited to the situation.
 2. The method as claimed inclaim 1, wherein the representative parameter analyzed is obtained fromthe speed of the turbojet low pressure compressor shaft.
 3. The methodof claim 1, wherein the operating sequence executed is chosen from atleast two predetermined sequences that correspond to instances in whichthe turbojet is operating at low speed and at high speed, respectively.4. The method of claim 1, wherein when the operating sequence is beingexecuted, the electric motor delivers a torque less than or equal to amaximum limit value.
 5. The method of claim 4, wherein when the value ofthe parameter representative of the turbojet speed lies within apredetermined range, the maximum limit value on the torque delivered bythe electric motor is determined by applying a function similar to thevalue of the representative parameter.
 6. The method of claim 3, whereinthe operating sequence executed for a turbojet operating at low speedcomprises a test step for testing the operating status of the electricmotor which, in the event that the latter is not operating, will causethe operating sequence intended for a turbojet operating at a higherspeed to be applied.
 7. The method of claim 1, wherein at least at thestart of the operating sequence, the speed of the electric motor islimited.
 8. The method of claim 1, wherein the operating sequenceexecuted comprises at least one step of checking and regulating thespeed.
 9. The method of claim 1, wherein the operating sequencecomprises a control loop for checking the operating status of theelectric motor and capable of shutting this electric motor down.
 10. Themethod of claim 1, wherein provision is made for an operating sequenceto be initiated by default if the representative parameter cannot beanalyzed.
 11. A thrust reverser comprising at least one moving coverthat can be moved under the action of at least one electric motor,wherein the electric motor is controlled via at least one controlinterface capable, in succession, of analyzing at least one parameterrepresentative of the turbojet speed and of delivering at least onesuitable operating datum value.
 12. The reverser as claimed in claim 11,wherein the control interface is connected to a turbojet control unitdelivering the representative parameter.
 13. The reverser of claim 11,wherein the electric motor is a self-controlled synchronous motor (7).14. The reverser of claim 11, wherein the electric motor is torquecontrolled at constant speed.
 15. The reverser of claim 14, wherein thecontrol interface comprises regulating means for regulating the torquedelivered by the electric motor.
 16. The reverser of claim 14, whereinthe control interface is capable of receiving a speed datum value and ofconverting it into a torque instruction that it delivers to the electricmotor.
 17. The reverser of claim 16, wherein the control interfacecomprises regulating means for regulating the speed of the electricmotor.